var arr = ['短跑','接力','拔河','跳绳','接力','拔河','跳远']
function unique(arr) {
    var newArr = {}
    for (var i = 0; i < arr.length; i++) {
        if (newArr.indexOf(arr[i]) == -1){
            newArr.push(arr[i])
        }
        return newArr
    }
}
console.log(unique(arr));